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  <title>promise的几个关键问题3</title>
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  <script>
    /* 
    4.	promise.then()返回的新promise的结果状态由什么决定?
      (1)简单表达: 由then()指定的回调函数执行的结果决定
      (2)详细表达:
          ①如果抛出异常, 新promise变为rejected, reason为抛出的异常
          ②如果返回的是非promise的任意值, 新promise变为resolved, value为返回的值
          ③如果返回的是另一个新promise, 此promise的结果就会成为新promise的结果 
    */

    new Promise((resolve, reject) => {
      // resolve(1)
      reject(1)
    }).then(
      value => {
        console.log('onResolved1()', value)
        // return 2
        // return Promise.resolve(3)
        // return Promise.reject(4)
        throw 5
      },
      reason => {
        console.log('onRejected1()', reason)
        // return 2
        // return Promise.resolve(3)
        // return Promise.reject(4)
        throw 5
      }
    ).then(
      value => {
        console.log('onResolved2()', value)
      },
      reason => {
        console.log('onRejected2()', reason)
      }
    )

  </script>
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